This is a long-term study of endemic cretinism and of the retarded physical and neurological development which often accompanies severe endemic goiter. The project site is in two villages of rural highland Ecuador, where endemic goiter is unusually severe and where the maize diet is low in protein and calories. For this final year of committed support for the project, the objective is to reduce and analyze the data which have been accumulated on the effects of giving daily lysine-tryptophan supplements, or both, to pregnant women as early in pregnancy as possible and continuing through the lactation period. Physical growth, and intellectual and neurological development of the progeny have been monitored during the course of the project which is now in its fourth year.